Coating systems for cement composite articles

ABSTRACT

A coating system, a method of coating a substrate, and a coated substrate (e.g., a coated cement fiberboard article) include one or more latex polymers, an aliphatic epoxy resin system, optionally a silicate additive, and optionally one or more olefinic compounds and an initiator. The coating system may be applied in one or more layers and may be applied to all the surfaces of the substrate (e.g., the front side, back side and edges of a board). The coated substrate may then be coated with other optional coatings, e.g., decorative or protective topcoats.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional Application Ser.No. 60/819,505, filed Jul. 7, 2006, and from U.S. ProvisionalApplication Ser. No. 60/898,621, filed Jan. 30, 2007, the disclosures ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Cement composite articles are becoming more and more common for use inbuilding materials. Many of these articles are prepared from inexpensivematerials, such as cement, wood (cellulose) fibers, natural (glass)fibers and polymers. These articles usually are prepared in the form ofcement fiberboard substrates such as siding panels and boards. Thesubstrate or articles can be made using methods such as extrusion orusing a Hatschek process.

In northern climates, damage from repeated freezing and thawing of waterabsorbed into the cement fiberboard substrate represents a significantproblem. Continued exposure to moisture, freeze-thaw cycles, UV exposureand atmospheric carbon dioxide can cause physical and chemical changesin articles made from cement fiberboard compositions over time and alsodamage decorative surfaces. Coating systems or coating compositions canhelp prevent exposure to the elements such as UV light, carbon dioxideand water, or can help reduce the damage that can occur due to exposureto these elements. Several such systems are available for protectingcement fiberboard articles. However, there is a need for coating systemsand coating compositions that provide a superior seal, have the abilityto cure rapidly or can provide improved results when an article coatedwith the composition is submitted to wet adhesion testing and multiplefreeze-thaw cycles.

SUMMARY

The present invention provides in one aspect a coating compositionhaving one or more latex polymers, and an aliphatic epoxy resin system.In certain embodiments the aliphatic epoxy resin is distinct from theone or more latex polymers. In other embodiments the aliphatic epoxyresin is part of one or more of the one or more latex polymers. Theoxirane functional component in the aliphatic epoxy resin system can, incertain embodiments, have an epoxy equivalent weight less than about1000. The coating composition can include one or more coatingcompositions that may be applied in one or more layers.

In another aspect the invention provides a coated article comprising acement fiberboard substrate and a coating system applied to thesubstrate. The article includes a first coating system applied to thesubstrate, wherein the first coating system includes an aliphatic epoxyresin system having one or more aqueous dispersions of polymerparticles, optionally a silicate additive, and optionally one or moreolefinic compounds and initiator for same. The first coating systempreferably includes one or more coating compositions that may be appliedin one or more layers. In a preferred embodiment, the aqueous polymerdispersion is a latex polymer, the epoxy resin system comprisestrimethylol propane triglycidyl ether and an amine, and the optionalsilicate additive comprises potassium silicate. In another preferredembodiment, each of the coating compositions is an aqueous composition.

In another aspect, the coated article includes: a cement fiberboardsubstrate, and a first coating system applied to the substrate, whereinthe first coating system includes: an epoxy-functional latex polymer, anamine solution, optionally a silicate additive, and optionally one ormore olefinic compounds and initiator for same.

In another aspect, an optional second coating system may be applied ontop of the first coating system. The optional second coating systempreferably comprises a functionalized latex polymer or a multistagelatex polymer or a functionalized, multistage latex polymer. Morepreferably, the optional second coating system comprises anacetoacetoxy-functional multistage latex polymer.

In another aspect, the invention provides a method for preparing acoated article, which method comprises providing a cement fiberboardsubstrate, coating at least a portion of the substrate with theabove-described coating system and radiation-curing the coating.

The above summary of the present invention is not intended to describeeach disclosed embodiment or every implementation of the presentinvention. Other features, objects, and advantages of the invention willbe apparent from the description and drawings, and from the claims. Thedescription that follows more particularly exemplifies illustrativeembodiments. In several places throughout the application, guidance isprovided through lists of examples, which examples can be used invarious combinations. In each instance, the recited list serves only asa representative group and should not be interpreted as an exclusivelist.

The details of one or more embodiments of the invention are set forth inthe accompanying drawing and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic cross-sectional view of a coated fiber cementarticle.

Like reference symbols in the various figures of the drawing indicatelike elements. The elements in the drawing are not to scale.

DETAILED DESCRIPTION

An “epoxy coating system” or “epoxy resin system” or “epoxy functionallatex system” means a multi-component coating system having at least twocomponents, a first component having oxirane groups (e.g.,epoxy-functional coating composition or epoxy functional latex polymer)and a second component having reactive groups (e.g., epoxide-reactivefunctional groups) that can react with the oxirane group. These groupscan react to cure, polymerize or crosslink the coating system.

An aqueous dispersion of polymer particles encompasses the meaning oflatex polymer and water dispersible polymer.

A “latex” polymer means a dispersion or emulsion of polymer particlesformed in the presence of water and one or more secondary dispersing oremulsifying agents (e.g., a surfactant, alkali-soluble polymer ormixtures thereof) whose presence is required to form the dispersion oremulsion. The secondary dispersing or emulsifying agent is typicallyseparate from the polymer after polymer formation. In some embodiments areactive dispersing or emulsifying agent may become part of the polymerparticles as they are formed.

A “water-dispersible” polymer means a polymer which is capable of beingcombined by itself with water, without requiring the use of a secondarydispersing or emulsifying agent, to obtain an aqueous dispersion oremulsion of polymer particles having at least a one month shelfstability at normal storage temperatures.

The term “multistage” when used with respect to a latex means the latexpolymer was made using discrete charges wherein each charge contains oneor more monomers or was made using a continuously-varied charge of twoor more monomers. Usually a multistage latex will not exhibit a singleTg inflection point as measured using DSC. For example, a DSC curve fora multistage latex made using discrete charges of one or more monomersmay exhibit two or more Tg inflection points. Also, a DSC curve for amultistage latex made using a continuously-varied charge of two or moremonomers may exhibit no Tg inflection points. By way of furtherexplanation, a DSC curve for a single stage latex made using a singlemonomer charge or a non-varying charge of two monomers may exhibit onlya single Tg inflection point. Occasionally when only one Tg inflectionpoint is observed, it may be difficult to determine whether the latexrepresents a multistage latex. In such cases a lower Tg inflection pointmay sometimes be detected on closer inspection, or the synthetic schemeused to make the latex may be examined to determine whether or not amultistage latex would be expected to be produced.

The terms “a,” “an,” “the,” “at least one,” and “one or more” are usedinterchangeably. Thus, for example, a coating composition that comprises“an” amine can be interpreted to mean that the coating compositionincludes “one or more” amines.

The recitation of numerical ranges by endpoints includes all numberssubsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3,3.80, 4, 5, etc.).

The term “comprises” and variations thereof does not have a limitingmeaning where such term appears in the description or claims. Thus, forexample, a composition comprising a wax compound means that thecomposition includes one or more wax compounds.

The terms “acrylate esters” and “methacrylate esters” refer to esters ofacrylic acid and ester's of methacrylic acid, respectively. They may bereferred to as (meth)acrylates or (meth)acrylate ester's.

The term “olefinic compound” refers to any monomer, oligomer or polymercontaining reactive ethylenic unsaturation, such as vinyls,(meth)acrylates, vinyl ethers, allyl ethers, vinyl esters, unsaturatedoils (including mono, di and triglycerides), unsaturated fatty acids,and the like. The term “olefinic group” refers to the reactive ethylenicunsaturated functional group in an olefinic compound.

The terms “preferred” and “preferably” refer to embodiments that mayafford certain benefits, under certain circumstances. However, otherembodiments may also be preferred, under the same or othercircumstances. Furthermore, the recitation of one or more preferredembodiments does not imply that other embodiments are not useful, and isnot intended to exclude other embodiments from the scope of theinvention.

The term “organic group” refers to a hydrocarbon (e.g., hydrocarbyl)group with optional elements other than carbon and hydrogen in thechain, such as oxygen, nitrogen, sulfur, and silicon that is classifiedas an aliphatic group, cyclic group, or combination of aliphatic andcyclic groups (e.g., alkaryl or aralkyl groups). The term “aliphaticgroup” refers to a saturated or unsaturated linear or branchedhydrocarbon group. For example, this term is used to encompass alkyl,alkenyl, and alkynyl groups. The term “alkyl group” refers to asaturated linear or branched hydrocarbon group including, for example,methyl, ethyl, isopropyl, t-butyl, heptyl, dodecyl, octadecyl, amyl,2-ethylhexyl, and the like. The term “alkenyl group” refers to anunsaturated linear or branched hydrocarbon group with one or morecarbon-carbon double bonds. Non-limiting examples of alkenyl groupsinclude groups such as vinyl, 1-propenyl, 2-propenyl, 1,3-butadienyl,1-butenyl, 2-butenyl, 1-pentenyl, 2-pentenyl, 1-hexenyl, 2-hexenyl,heptenyl, octenyl and the like. The term “alkynyl group” refers to anunsaturated linear or branched hydrocarbon group with one or morecarbon-carbon triple bonds. Non-limiting examples of alkynyl groupsinclude ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl,3-butynyl, 1-pentynyl, 2-pentynyl, 1-hexynyl, 2-hexynyl, heptynyl,octynyl and the like. The term “cyclic group” refers to a closed ringhydrocarbon group that can be classified as an alicyclic group, aromaticgroup (aryl group), or heterocyclic group. The term “alicyclic group”refers to a cyclic hydrocarbon group having properties resembling thoseof aliphatic groups. Non-limiting examples of alicyclic groups includecyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclooctyl and the like. The terms “aromatic group” or “aryl group”refer to a mono- or polycyclic aromatic hydrocarbon group such as phenylor naphthyl. The term “heterocyclic group” refers to a closed ringhydrocarbon group in which one or more of the atoms in the ring is anelement other than carbon (e.g., nitrogen, oxygen, sulfur, etc.).

Substitution can occur on the organic groups of the coalescents used inthe coating compositions of the present invention. As a means ofsimplifying the discussion and recitation of certain terminology usedthroughout this application, the terms “group” and “moiety” are used todifferentiate between chemical species that allow for substitution orthat may be substituted and those that do not allow or may not be sosubstituted. Thus, when the term “group” is used to describe a chemicalsubstituent, the described chemical material includes substituted andunsubstituted groups, where the substituent groups can include O, N, Si,or S atoms, for example, in the chain (e.g., an alkoxy group) as well ascarbonyl groups and other conventional substituent groups. For example,the phrase “alkyl group” is intended to include not only pure open chainsaturated hydrocarbon alkyl substituents, such as methyl, ethyl, propyl,t-butyl, and the like, but also includes substituted alkyl groups havingsubstituents known in the art, such as hydroxy, alkoxy, alkylsulfonyl,halogen atoms, cyano, nitro, amino, carboxyl, and the like. Thus, “alkylgroup” can include ether groups, haloalkyls, nitroalkyls, carboxyalkyls,hydroxyalkyls, sulfoalkyls, and the like. When the term “moiety” is usedto describe a chemical compound or substituent, only the unsubstitutedchemical material is intended to be included. Thus, the phrase “alkylmoiety” is limited to the inclusion of only pure open chain saturatedhydrocarbon alkyl substituents, such as methyl, ethyl, propyl, t-butyl,and the like. The term “hydrocarbyl moiety” refer's to unsubstitutedorganic moieties containing only hydrogen and carbon.

In one aspect, the invention provides a coating system for a widevariety of substrates, including, for example, fiber cement substrates,such as a cement fiberboard siding product or other cement compositearticle. Although reference is made throughout this specification tofiber cement substrates, the coating compositions described herein mayalternatively be used with a wide variety of other substrates. Suitablesuch other substrates include wood, metal, cement, plastic, ceramic,glass, composites, etc.

Preferably, the first coating system includes an aqueous dispersion ofpolymer particles (e.g., a latex polymer or polyurethane dispersion, ora mixture of both), an aliphatic epoxy resin system, optionally asilicate, and optionally one or more olefinic compounds. Alternatively,the first coating system includes: an aliphatic epoxy resin systemcontaining an epoxy-functional latex polymer, optionally a silicateadditive, and optionally one or more olefinic monomers or oligomers andinitiator for same.

In preferred embodiments, the coating system has the adhesion andwater-resistance properties of an epoxy system and the weatheringproperties of a latex or water-dispersible polymer coating.

Referring to FIG. 1, a coated article 10 of the present invention isshown in schematic cross-sectional view. Article 10 includes a cementfiberboard substrate 12. Substrate 12 typically is quite heavy and mayfor example have a density of about 1 to about 1.6 g/cm³ or more. Thefirst major surface 14 of substrate 12 may be embossed with small peaksor ridges 16 and valleys 18, e.g., so as to resemble roughsawn wood.Major surface 14 may have a variety of other surface configurations, andmay resemble a variety of building materials other than roughsawn wood.Layer or layers 20 of the disclosed coating system lie atop andpartially penetrate surface 14, and desirably are applied to article 10at the location where article 10 is manufactured. Layer(s) 20 help toprotect substrate 12 against one or more of exposure to moisture,freeze-thaw cycles, UV exposure or atmospheric carbon dioxide. Layer(s)20 also may provide a firmly-adhered base layer upon which one or morefirmly-adhered layers of final topcoat 22 may be formed. Final topcoat22 desirably is both decorative and weather-resistant, and may beapplied to article 10 at the location where article 10 is manufacturedor after article 10 has been attached to a building or other surface.

A variety of cement fiberboard substrates may be employed in thedisclosed articles. The disclosed substrates typically include cementand a filler. Exemplary filler's include woods, fiberglass, polymers(organic and inorganic) or mixtures thereof. The substrates can be madeusing methods such as, extrusion, the Hatschek method, or other methodsknown in the art. See, e.g., U.S. Patent Application No. 2005/0208285 A1(corresponds to International Patent Application No. WO 2005/071179 A1);Australian Patent Application No. 2005/00347; International PatentApplication No. WO 01/68547 A1; International Patent Application No. WO98/45222 A1; U.S. Patent Application No. 2006/0288909 A1; and AustralianPatent Application No. 198060655 A1. Non-limiting examples of suchsubstrates include siding products, boards and the like, for usesincluding fencing, roofing, flooring, wall boards, shower boards, lapsiding, vertical siding, soffit panels, trim boards, shaped edge shinglereplicas and stone or stucco replicas. One or both major surfaces of thesubstrate may be profiled or embossed to look like a grained orroughsawn wood or other building product, or scalloped or cut toresemble shingles. The uncoated substrate surface typically contains aplurality of pores with micron- or submicron-scale cross-sectionaldimensions.

A variety of suitable fiber cement substrates are commerciallyavailable. For example, several preferred fiber cement siding productsare available from James Hardie Building Products Inc. of Mission Viejo,Calif., including those sold as HARDIEHOME™ siding, HARDIPANEL™ verticalsiding, HARDIPLANK™ lap siding, HARDIESOFFIT™ panels, HARDITRIM™ planksand HARDISHINGLE™ siding. These products are available with an extendedwarranty, and are said to resist moisture damage, to require only lowmaintenance, to not crack, rot or delaminate, to resist damage fromextended exposure to humidity, rain, snow, salt air and termites, to benon-combustible, and to offer the warmth of wood and the durability offiber cement. Other suitable fiber cement siding substrates includeAQUAPANEL™ cement board products from Knauf USG Systems GmbH & Co. KG ofIserlohn, Germany, CEMPLANK™, CEMPANEL™ and CEMTRIM™ cement boardproducts from Cemplank of Mission Viejo, Calif.; WEATHERBOARDS™ cementboard products from CertainTeed Corporation of Valley Forge, Pa.;MAXITILE™, MAXISHAKE™ AND MAXISLATE™ cement board products from MaxiTileInc. of Carson, Calif.; BRESTONE™, CINDERSTONE™, LEDGESTONE™, NEWPORTBRICK™, SIERRA PREMIUM™ and VINTAGE BRICK™ cement board products fromNichiha U.S.A., Inc. of Norcross, Ga., EVERNICE™ cement board productsfrom Zhangjiagang Evernice Building Materials Co., Ltd. of China and EBOARD™ cement board products from Everest Industries Ltd. of India.

In one embodiment, the present invention provides a first coating systemfor a cement fiberboard article. In cement fiberboard manufacturingprocesses, freshly coated boards exit the manufacturing line and arestacked. It is desirable to manufacture the products as efficiently aspossible. Consequently, there is an ever-present desire to speed up theprocess or utilize less energy during the process (e.g., utilizing asmaller oven). In other words, the coatings applied to the products arepreferably dried as quickly and efficiently as possible. Onerequirement, however, that frustrates this desire is that freshly coatedboards preferably should not “block” when stacked (e.g., the coatedboards should not stick together). One mechanism to lessen the tendencyfor a freshly applied coating to block is to use a higher Tg resin.Unfortunately, however, higher Tg resins may require the use of acoalescent solvent to facilitate film formation, and many traditionalcoalescent solvents are volatile and/or cause regulatory concerns. Toovercome these difficulties, the disclosed compositions provide ablock-resistant system that achieves proper coalescence without using avolatile reactive coalescing agent. As discussed in more detail below,it has been discovered that the combination of a high Tg latex with analiphatic epoxy resin system gives a low-VOC coating with improvedadhesion and freeze thaw performance. While not wishing to be bound bytheory, it appears that the uncured epoxy resin system functions as aneffective coalescent agent to the latex component.

In another embodiment, a two-component aliphatic epoxy coating system isapplied to a substrate and is then over-coated with a second coatingsystem. The use of an aliphatic epoxy system (as opposed to an aromaticepoxy system) in the first coating system permits the line to be rununder conditions where the first coating system is not fully dried priorto the application of the second coating system. While not wishing to bebound by theory, it is presently believed that uncured epoxy resins maymigrate into a subsequently applied coating system. The disclosedaliphatic epoxy resins, unlike most aromatic epoxy resins, do notexhibit undesirable amounts of “chalking” upon exposure to UV light.This is especially advantageous when the coated substrate is going to beexposed to sunlight for prolonged periods of time.

The term “aliphatic epoxy” means the epoxy resin is not principallyderived from phenol or substituted phenol compounds (e.g., phenylphenol, butyl phenol, nonyl phenol, cresol, bisphenol A, bisphenol F,butoxymethylolated bisphenol A, novolac phenolics, resoles phenolics,and the like). The term “aliphatic epoxy” does, however, encompassepoxy-functional latex polymers (e.g., GMA-based latex polymers), whichthemselves may have been formed using non-phenol-containing aromaticmonomers such as styrene. Preferably, the aliphatic epoxy-functionalresins will be derived from compounds having less than about 5% aromaticalcohol groups, e.g., phenol, phenyl phenol, butyl phenol, nonyl phenol,cresol, bisphenol A, bisphenol F, butoxymethylolated bisphenol A,novolac phenolics, resoles phenolics, and the like) based on the totalweight of the aliphatic epoxy-functional resin. More preferably, thealiphatic epoxy-functional resins will be derived from compounds havingless than about 3% aromatic alcohol groups. Most preferably, thealiphatic epoxy-functional resins will be derived from compounds havingless than about 1% aromatic alcohol groups. In addition, the term“aliphatic epoxy” does encompass epoxy-functional resins made, forexample, as the reaction product of an oxirane precursor molecule (e.g.,epichlorohydrin) and a non-phenol-containing aromatic acids (e.g.,isophthalic acid). The term “aliphatic epoxy” also encompasses epoxyresins principally derived from phenol or substituted phenols where thearomatic ring structure of the phenol or substituted phenol has beenhydrogenated (e.g., hydrogenated bisphenol A).

The use of an aliphatic epoxy resin system provides yet anotheradvantage in preferred coating systems. In another embodiment, thepresent invention provides 2-component aliphatic epoxy systems thatfunction as one-coat systems. In this embodiment, a cement fiberboardproduct is provided that includes a first coating of an aliphatic epoxyresin system. The coating is suitable for prolonged exterior exposuresuch as might be experienced in advance of a field-applied topcoat. Inother words, a coated cement fiberboard article is provided thatexhibits acceptable weathering and freeze thaw properties. The articlecan be installed as received from the manufacturer and then a finalcoating of architectural paint can be applied. In preferred embodimentsthe product can withstand the elements for six months prior to the finalcoating being applied.

In another embodiment the coating system includes a two-part system,with a first part including a latex polymer solution, an epoxy resindispersed in the solution and optional additives (e.g., defoamers,wetting agents, flatting agents, dyes, pigments, etc.), and a secondpart having an amine solution, together with optional additives (e.g.,defoamers, wetting agents, flatting agents, dyes, pigments, etc.),optional silicate salt or optional additional latex polymer.

In yet another embodiment, the coating system includes a two-partsystem, with a first part including an epoxy-functional latex polymersolution and optional additives (e.g., defoamers, wetting agents,flatting agents, dyes, pigments, etc.), and a second part having anamine solution, together with optional additives (e.g., defoamers,wetting agents, flatting agents, dyes, pigments, etc.), optionalsilicate salt or optional additional latex polymer (not beingepoxy-functional).

In the embodiment having two parts, the two parts are mixed to form thefirst coating system in a conventional manner and applied to thearticle, or they may be applied to the article as described inInternational Patent Application Serial No. PCT/US2007/002347.

The first coating system includes one or more coating compositions thatmay be applied in one or more layers. In certain embodiments, each ofthe one or more coating compositions is an aqueous composition.

In one embodiment, the first coating system includes a latex polymer andan aliphatic epoxy resin system. Examples of specific coatingcompositions for this embodiment include: (i) a latex polymer, and analiphatic epoxy resin system, (ii) a latex polymer, an aliphatic epoxyresin system, and a silicate salt, (iii) a latex polymer, an aliphaticepoxy resin system, an olefinic monomer, and a silicate salt, (iv) alatex polymer, an aliphatic epoxy resin system, a silicate salt, and oneor more pigments, (v) an epoxy functional latex polymer system and asilicate salt, or (vi) an epoxy functional latex polymer system, asilicate salt, and one or more pigments. In preferred embodiments, theepoxy resin system is a two-part system with a first part containing anepoxy functional resin and a second part containing a compound that isreactive with the epoxy groups (e.g., an amine compound). One exemplarycoating composition, based upon non-volatile components, includes: 5-50wt. % aliphatic epoxy resin with an epoxy equivalent weight (EEW)between 75 and 1,000; 20-80 wt. % latex polymer with a preferred Tg of5-50° C.; 2-15 wt. % amine crosslinker with a reactive hydrogenequivalent weight between 20 and 500; and 0-40 wt. % silicate salt.Preferred 2-component systems have pot lives in excess of 2 hours at25.6° C. (78° F.) or are applied as described in International PatentApplication Serial No. PCT/US2007/002347.

The disclosed coating compositions may be used in place of or inaddition to prior art “sealers”, “primers”, and “topcoats”. However, thedisclosed compositions may not fit neatly into either category per seand such terms should not be limiting.

The articles are coated on one or more surfaces with an aqueous coatingsystem. The coating system includes one or more coating compositionsthat may be applied in one or more layers.

Preferred coating systems may also include one or more of the followingadditional features:

-   -   low VOC;    -   increasing the resistance of the article to water uptake (into        the article);    -   improving or promoting adhesion of additional coatings to the        article surface (e.g., topcoats);    -   increasing the surface integrity of the article (e.g., by acting        to reinforce the fiber and cement matrix much like binder in        other composite materials);    -   protecting against expansion of the article under freeze/thaw        conditions; or    -   increasing the integrity of the edges of the article by binding        the fiber layers together,    -   block resistance.

Exemplary first coating systems include an aqueous dispersion of polymerparticles, an aliphatic epoxy resin system, optionally a silicate salt,optionally one or more olefinic monomers or oligomers, and optionaladditives (e.g., defoamers, wetting agents, flatting agents, dyes,pigments, etc.).

Exemplary aqueous dispersions of polymer particles for use in the firstcoating systems are latex polymers, polyurethanes, polyamides,chlorinated polyolefins, acrylics, vinyls, oil-modified polymers,polyesters, and mixtures or copolymers thereof. More preferably, theaqueous dispersions of polymer particles is a latex or water-dispersiblepolyurethane.

In one optional embodiment, the multi-component composition may includean aqueous dispersion of polymer particles, a silicate salt, optionaladditives (e.g., defoamers, wetting agents, flatting agents, dyes,pigments, etc.), and optionally one or more olefinic monomers oroligomers as described in U.S. Patent Application Ser. No. 60/764,044,which is herein incorporated by reference. These additional ingredientsmay be added to any of the components, though it is preferred to add theaqueous dispersion of polymer particles with the epoxy component. In oneembodiment, the multi-component composition, when combined, will includea latex polymer, potassium silicate, an epoxy oligomer (e.g., ahydrogenated bisphenol A containing epoxy oligomers), a polymeric aminecrosslinker, and water.

A variety of polymeric materials may be employed in the disclosedaqueous dispersions of polymer particles, including (meth)acrylics,vinyls, oil-modified polymers, polyesters, polyurethanes, polyamides,chlorinated polyolefins, and mixtures or copolymers thereof. Latexpolymers are readily synthesized at modest cost and provide a preferredclass of aqueous dispersions of polymer particles. Latex polymers aretypically prepared through chain-growth polymerization, using one ormore olefinic compounds (preferably monomers). Non-limiting examples ofolefinic compounds which may be used to prepare latex polymers includeethylene, butadiene, propene, butene, iso-butene, acrylic acid,methacrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate,butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethylmethacrylate, propyl methacrylate, butyl methacrylate, t-butylmethacrylate, 2-ethylhexyl methacrylate, hydroxyethyl acrylate,hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxybutylacrylate, hydroxybutyl methacrylate, glycidyl methacrylate, glycidylacrylate, 4-hydroxybutyl acrylate glycidylether, acrylamide,methylacrylamide, styrene, α-methyl styrene, t-butyl styrene, vinyltoluene, vinyl acetate, vinyl propionate, allyl methacrylate,acetoacetyl ethyl methacrylate (AAEM), diacetone acrylamide,dimethylaminomethacrylate, dimethylaminomethacrylate,N-hydroxy(meth)acrylamide, vinyl ether maleate/fumarate, vinyl esters ofVERSATIC™ acid (VERSATIC acid is a synthetic saturated monocarboxylicacid of highly branched structure containing about 5 to about 10 carbonatoms), and mixtures thereof. Preferably, the latex polymer is a(meth)acrylic polymer.

The latex polymers are typically stabilized using one or more nonionicor anionic emulsifiers (viz., surfactants), used either alone ortogether. Examples of nonionic emulsifiers includetert-octylphenoxyethylpoly(39)-ethoxyethanol,dodecyloxypoly(10)ethoxyethanol,nonylphenoxyethyl-poly(40)ethoxyethanol, polyethylene glycol 2000monooleate, ethoxylated castor oil, fluorinated alkyl esters andalkoxylates, polyoxyethylene (20) sorbitan monolaurate, sucrosemonococoate, di(2-butyl)phenoxypoly(20)ethoxyethanol,hydroxyethylcellulosepolybutyl acrylate graft copolymer, dimethylsilicone polyalkylene oxide graft copolymer, poly(ethyleneoxide)poly(butyl acrylate) block copolymer, block copolymers ofpropylene oxide and ethylene oxide,2,4,7,9-tetramethyl-5-decyne-4,7-diol ethoxylated with 30 moles ofethylene oxide, N-polyoxyethylene(20)lauramide,N-lauryl-N-polyoxyethylene(3)amine and poly(10)ethylene glycol dodecylthioether. Examples of anionic emulsifiers include sodium laurylsulfate, sodium dodecylbenzenesulfonate, potassium stearate, sodiumdioctyl sulfosuccinate, sodium dodecyldiphenyloxide disulfonate,nonylphenoxyethylpoly(1)ethoxyethyl sulfate ammonium salt, sodiumstyrene sulfonate, sodium dodecyl allyl sulfosuccinate, linseed oilfatty acid, sodium, potassium, or ammonium salts of phosphate esters ofethoxylated nonylphenol or tridecyl alcohol, sodiumoctoxynol-3-sulfonate, sodium cocoyl sarcocinate, sodium1-alkoxy-2-hydroxypropyl sulfonate, sodium alpha-olefin (C₁₄-C₁₆)sulfonate, sulfates of hydroxyalkanols, tetrasodium N-(1,2-dicarboxyethyl)-N-octadecylsulfosuccinamate, disodiumN-octadecylsulfosuccinamate, disodium alkylamido polyethoxysulfosuccinate, disodium ethoxylated nonylphenol half ester ofsulfosuccinic acid and the sodium salt oftert-octylphenoxyethoxypoly(39)ethoxyethyl sulfate and the like. Inaddition, combinations of emulsifiers can be used.

If desired, the latex polymers may be stabilized with an alkali-solublepolymer. Alkali-soluble polymers may be prepared by making a polymerwith acrylic or methacrylic acid or other polymerizable acid monomer(usually greater than 7%) and solubilizing the polymer by addition ofammonia or other base. See, e.g., published U.S. Patent Application Nos.2006/0135684 A1, 2006/0135686 A1. Examples of alkali-soluble polymersinclude JONCRYL™ 675 and JONCRYL 678. One exemplary process forpreparing alkali soluble polymers is outlined in U.S. Pat. No.5,962,571.

Latex polymers having some acidic functionality are sometimes furtherstabilized by neutralization using ammonia or an amine. It has beendiscovered that neutralization or partial neutralization of a waterborneacetoacetyl-functional polymer with a nitrogen-containing base (e.g.,ammonia or an amine) can in some situations lead to an undesirableluminescence appearance in a clear coating. Although not intended to belimiting, it is believed that this appearance may be caused by theformation of a tautomeric enol configuration or enamine configuration.The use of a nitrogen-free base (e.g., an inorganic metal base such asKOH, CaOH, NaOH, LiOH, etc.) can solve or lessen this problem for thesetypes of coatings. Other such nitrogen-free bases may also be employedin this manner.

A water-soluble free radical initiator is typically used in thepolymerization of a latex polymer. Exemplary water-soluble free radicalinitiators are described below. The amount of initiator is preferablyfrom 0.01 wt. % to 3 wt. %, based on the total amount of monomer. In aredox system, the amount of reducing agent is preferably from 0.01 wt. %to 3 wt, %, based on the total amount of monomer. The reactiontemperature may be in the range of 10° C. to 100° C.

Exemplary commercially available latex polymers include AIRFLEX™ EF811(available from Air Products), EPS 2505 (available from EPS/CCA) andNEOCAR™ 2300, NEOCAR 820 and NEOCAR 2535 (available from Dow ChemicalCo.). Other exemplary latex polymers include the latex polymersdescribed in co-pending published U.S. Patent Application No.2007/0110981 A1. Preferred latex polymers are prepared at a pH of lessthan about 7.5, more preferably less than about 6.0, and most preferablyless than about 5.5. Preferred latex polymers are substantially free ofammonia, meaning the latex polymers contain less than about 1% ammoniaon polymer nonvolatiles, more prefer ably less than about 0.3% ammoniaon polymer nonvolatiles, and most preferably less than 0.1% ammonia onpolymer nonvolatiles.

The latex polymer may optionally also be functionalized with olefinicgroups or other crosslinkable groups where it is desired to enable thelatex polymer to participate in radiation curing. Exemplaryfunctionalized latex polymers, include ROSHIELD™ 3120 (available fromRohm & Haas) and the AAEM-functional latex polymers disclosed in U.S.patent application Ser. No. 11/300,070 filed Dec. 14, 2005 and Ser. No.11/342,412 filed Jan. 30, 2006, and in the above-mentioned applicationSer. No. 11/560,329.

Exemplary latex polymers include multistage latexes, as well asfunctionalized latexes (e.g., epoxy-functional latex, AAEM-functionallatexes, etc.), and multistage, functionalized latexes.

Preferred single-stage latex polymers have a glass transitiontemperature (Tg) of at least 5° C., more preferably at least 15° C., andmost preferably at least 25° C., and optimally at least 30° C. Preferredsingle-stage latex polymers for use have a Tg of less than 70° C., morepreferably less than 60° C., and most preferably less than 50° C.

Preferred multistage latex polymers have between 50 and 90 wt. % hardsegments and between 10 and 50 wt. % soft segments. The hard segmentpreferably has a Tg between 30 and 70° C., more preferably between 30and 130° C. and the soft segment preferably has a Tg between 0 and 25°C.

Preferred first components having oxirane groups have a minimum filmforming temperature (MFFT) less than about 30° C., more preferably lessthan about 20° C., and most preferably less than about 15° C. andoptimally less than about 10° C., when tested with a RHOPOINT™ 1212/42,MFFT Bar-60.

The first coating composition preferably includes an aliphatic epoxyresin system. Such aliphatic epoxy resin systems may includemulti-functional epoxy resins (e.g., di-, tri-, tetra-, and othermulti-functional epoxy resins) that are built using aliphaticcomponents. Examples of such multi-functional epoxy resins include thereaction products of epoxy containing compounds (e.g., epichlorohydrin)with multi-functional aliphatic alcohols or acids.

According to one embodiment, an epoxy coating system is applied to thefiber cement substrate. The epoxy coating system is typically amulti-component coating system that includes the epoxy coating systemsinclude those described in International Patent Application Serial No.PCT/US2007/002347. Epoxy-based coatings include multi-functionalepoxy-functional coatings, e.g., resins (e.g., di-, tri-, tetra-, andother multi-functional epoxy resins) that are prepared from aliphatic oraromatic starting materials. Aliphatic starting materials are presentlypreferred in cases where the starting material might be exposed forprolonged periods to UV radiation. Examples of such multi-functionalepoxy resins include the reaction products of epoxy containing compounds(e.g., epichlorohydrin) with multi-functional alcohols or acids. Anotherclass of aliphatic epoxies is derived from oxidized olefins, such aslimonene dioxide, epoxidized oils and the like.

In another embodiment, an epoxy resin can be prepared by reacting therequired proportions of an aliphatic polyol compound with an oxiraneprecursor molecule (e.g., epichlorohydrin). Procedures for suchreactions are generally known in the art and disclosed, for example, inU.S. Pat. No. 2,633,458. For example, epichlorohydrin may be reactedwith the following exemplary alcohol containing materials or carboxylicacid containing materials (or mixtures of such materials) to form anepoxy resin: ethylene glycol, propylene glycol, 1,3-propanediol,1,4-butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, neopentylglycol, 2,2-butylethyl propanediol, hexanediol, diethylene glycol,dipropylene glycol, polyethylene glycols, polypropylene glycols,cyclohexane dimethylol, 2,2,3-trimethylpentanediol, trimethyol propane(“TMP”), ethoxylated TMP, propoxylated TMP, glycerine, propoxylatedglycerine, pentaerythritol, ethoxylated pentaerythritol, propoxylatedpentaerythritol, dipentaerythritol, tripentaerythritol, ethoxylated andpropoxylated di and tri-pentaerythritol, ditrimethylolpropane,hydroxypivalyl hydroxypivalate, hydrogenated bisphenol A, ethoxylatedand propoxylated hydrogenated bisphenol A, isosorbide, malonic acid,succinic acid, glutaric acid, sebacic acid, fumaric acid, adipic acid,pimelic acid, hexahydrophthalic acid, 1,3- and 1,4cyclohexanedicarboxylic acid, orthophthalic acid, isophthalic acid,maleic acid, chlorendic acid, glycolic acid, citric acid, trimelliticacid, lactic acid, caprolactone and the like. Other alcohols or acidsmay be used as well. Preferred alcohols include, neopentyl glycol,trimethylolpropane, and hydrogenated bisphenol A.

Preferred epoxy resins distinct from the aqueous dispersion of polymerparticles are characterized by a molecular structure that includes atleast one oxirane chemical group. The epoxy resins may be a lowmolecular weight molecule (e.g., having a weight average molecularweight less than about 1000 Daltons), or may be in the form of a highermolecular weight molecule (e.g., having a weight average molecularweight greater than about 1000 Daltons). Preferred epoxy resins have amolecular weight between 200 and 25,000, more preferably between 200 and10,000, and most preferably between 200 and 2,000 Daltons. Preferredepoxy resins have an epoxy equivalent weight (EEW) of EEW of betweenabout 75 and 1,000, more preferably between about 85 and 800, and mostpreferably between about 90 and 350, and optimally between 90-250gm/epoxy group. Preferred aliphatic epoxy resins have a functionality ofbetween about 1 and 5, more preferably between about 1.5 and 4, and mostpreferably between about 2 and 3.5. In some embodiments, the epoxy resinhas a plurality of oxirane groups and is capable of functioning as across-linker. In this embodiment, the epoxy functional polymer couldcrosslink with the amine present in the two-component epoxy.

First coating compositions preferably include at least about 2 wt %,more preferably include at least about 3 wt % and most preferablyinclude at least about 4 wt % aliphatic epoxy resin based upon totalweight solids of the epoxy coating system. First coating compositionsalso preferably include less than about 40 wt %, more preferably includeless than about 30 wt % and most preferably include less than about 15wt % aliphatic epoxy resin based upon total weight solids of the epoxycoating system.

The epoxy resin can be reacted or crosslinked with an active hydrogencompound, such as amines, acids, acetoacetyl, hydroxyl, etc. Exemplaryamines include amidoamines such as the EPIKURE™ 3000 series from Hexion,polyamines such as the EPIKURE 3100 series from Hexion, aliphatic andmodified aliphatic amines such as the EPIKURE 3200 series from Hexion,cycloaliphatic amines such as the EPIKURE 3300 series from Hexion,waterborne/water dispersed amines such as EPIKURE 6870, 8290, 8535,8536, 8537 and 8540 from Hexion, dicyandiamides such as the Omnicure DDAseries from CVC Specialty Chemicals, polyoxyalkyleneamines such as theJEFFAMINE™ series (M, D, ED, EDR, T, SD, ST, HK, and XTJ) from Huntsman,amino functional phenolic resins (e.g. benzoguanamine) as well as othermonomeric amines such as isophorone diamine, piperazine, and the like.

The ratio of epoxy functionality to active hydrogen functionality (e.g.,amino-functionality) is generally controlled by the equivalent weightand mixing weight ratio of each component. Substrate morphology andporosity and the desired application viscosity determine the desiredoptimal ratio. Moreover, the epoxy-functional and activehydrogen-functional components may be applied at differing percentsolids (percent non-volatile material) or differing wet film thicknessesto obtain the desired mixing weight ratio. Preferably, the epoxy resinsystem has an oxirane group to active hydrogen group ratio of less thanabout 6:1, more preferably less than about 4:1 and most preferably lessthan about 2:1, and optimally less than about 1.4:1. Preferably, theepoxy resin system has an oxirane group to active hydrogen group ratioof greater than about 1:2, more preferably greater than about 1:1.5,most preferably greater than about 1:1.2 and optimally greater than1:1.1. In a preferred embodiment, the epoxy resin system has an oxiranegroup to active hydrogen group ratio of about 1:1.

In one embodiment, the aliphatic epoxy resin is incorporated into alatex polymer. For example, the epoxy resin-latex polymer blend can beprepared by (i) adding the epoxy resin directly to the latex polymer andmixing, (ii) mixing a pre-emulsified epoxy with the latex polymer, (iii)adding the epoxy resin to the latex monomer feed during the latexsynthesis, or (iv) mixing the epoxy resin and the latex polymer in astatic mixer and combining the mixture with a second componentcontaining an amine crosslinker, and applying to an article. The epoxycan also be applied by any of the methods outlined in InternationalPatent Application Serial No. PCT/US2007/002347.

Preferably, the aliphatic epoxy resin is added directly to the latexpolymer to form a first component of the epoxy coating system. Theactive hydrogen compound (e.g., the amine component) is provided in aseparate component of the epoxy coating system. By adding the aliphaticepoxy directly to the latex one can avoid the step of preparing aseparate epoxy resin dispersion.

Epoxy-functional latex polymers may also be used. When the latex polymeris formed using an epoxy functional monomer (such as glycidylmethacrylate, GMA) the epoxy functional monomer is preferably added tothe reaction vessel during the final portion of the monomer addition.Preferably, the epoxy-functional monomer is added during the last 50% ofthe monomer addition, more preferably, the epoxy-functional monomer isadded during the last 35% of the monomer addition, and most preferablythe epoxy-functional monomer is added during the last 20% of the monomeraddition. It is believed that by adding the epoxy-functional monomerlate in the reaction, the epoxy groups become incorporated into thepolymer particle in a better position to subsequently react with theepoxide-reactive functional groups (amine component).

It may also be advantageous to use a gradient latex polymer, which couldcontain various levels of the epoxy-functional monomer throughout thepolymer make up. For example, one may start with a monomer compositionsubstantially free or exempt of epoxy-functional monomer and then at acertain point in the polymerization start to feed a monomer compositioncontaining epoxy-functional monomer into the low or exemptepoxy-functional monomer feed. The resulting latex polymer can have agradient of epoxy functionality from low in the center of the polymerparticle to high on the surface of the polymer particle where it isbelieved that it would be in a better position to react with theepoxy-reactive functional groups.

Epoxy functional latex polymers preferably have an epoxy equivalentweight less than about 15,000, more preferably less than about 7,000,and most preferably less than about 4,000 based on the total weight ofthe latex polymer solids. Epoxy functional latex polymers preferablyhave an epoxy equivalent weight greater than about 450, more preferablygreater than about 1,000, and most preferably greater than about 1,600based on the total weight of the latex polymer solids.

In certain embodiments, one or both of the epoxide-reactive functionalgroups (e.g., amino-functional chemical compound) and theepoxy-functional coating composition (oxirane-functional chemicalcompound) may be chemically blocked to delay onset of chemical reactionuntil a desired time, at which time a stimulus is used to de-block thecomponents and permit reaction. For example, amine groups may be blockedto form a ketimene, which can unblock in the presence of moisture. Theblocked component may be heated to facilitate unblocking.

Preferred amino-functional chemical compounds are characterized by amolecular structure which includes at least one chemical group suchas >NH or —NH₂. The amino-functional chemical compound may be a lowmolecular weight molecule (e.g., having a weight average molecularweight less than about 1000 Daltons), or may be in a higher molecularweight molecule (e.g., having a weight average molecular weight greaterthan about 1000 Daltons). Preferred amino-functional compounds have amolecular weight between 100 and 30,000 Daltons, more preferably between200 and 10,000. Preferred amino-functional compounds have an amineequivalent weight of between 20 and 1500, more preferably between 20 and750, and most preferably between 20 and 300 gm/amine group. In someembodiments, the amino-functional chemical compound has a plurality ofamino groups and is capable of functioning as a cross-linker.

The disclosed coating systems may include one or more optionalwater-soluble silicate salts. Visual observation of coating compositionscontaining such silicate salts indicated that inclusion of the silicatesalt led to improved absorption of the coating composition into cementfiberboard substrates. Examples of silicate salts include lithiumsilicate, potassium silicate, sodium silicate, ammonium silicate and thelike. In preferred embodiments, the amount of silicate salt is fromabout 2 to about 50% by weight, more preferably from about 5 to about40% by weight and most preferably from about 10 to about 35% by weight,based on the total weight of the non-volatile components. Silicate saltsare available through a variety of chemical suppliers. For example,sodium silicate (sometimes referred to as waterglass) is available in avariety of forms including sodium orthosilicate (Na₄SiO₄), sodiummetasilicate (Na₂SiO₃), sodium polysilicate ((Na₂SiO₃)_(n)) and sodiumpyrosilicate (Na₆Si₂O₇). Sodium silicate and potassium silicate(sometimes referred to as potassium waterglass) are available from PQCorporation, Valley Forge, Pa.

A variety of olefinic compounds may be used in the disclosed coatingsystems. The olefinic compounds are carbon-containing compounds havingat least one site of unsaturation which can react, optionally in thepresence of an initiator, to provide polymeric or crosslinked products.Non-limiting examples of olefinic compounds include monomers such as(meth)acrylates, vinyls, vinyl ethers, allyl ethers, vinyl esters,unsaturated oils (including mono-, di- and tri-glycerides), unsaturatedfatty acids, and the like or mixtures thereof. The olefinic compoundsalso include oligomers or polymers having at least one site ofunsaturation which can react, optionally in the presence of aninitiator, to provide polymeric or crosslinked products.

Exemplary olefinic monomers include (meth)acrylate esters ofunsubstituted or substituted C₁-C₁₅ alcohols such as tripropyleneglycol, isobornyl alcohol, isodecyl alcohol, phenoxyethyl alcohol,tris-hydroxyethyl isocyanurate, trimethylolpropane ethoxylate,ditrimethylolpropane ethoxylate, hexanediol, ethoxylated neopentylglycol, propoxylated neopentyl glycol, ethoxylated phenol, polyethyleneglycol, bisphenol A ethoxylate, trimethylolpropane, propoxylatedglycerol, pentaerythritol, tetrahydrofurfuryl alcohol, β-carboxyethylalcohol, or combination thereof. For example, the olefinic monomer maybe isobornyl (meth)acrylate, isodecyl (meth)acrylate, phenoxyethyl(meth)acrylate, trimethylolpropane tri(meth)acrylate, alkoxylatedcyclohexane dimethanol di(meth)acrylate, trimethylolpropane ethoxylatetri(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropyleneglycol di(meth)acrylate, hexanediol di(meth)acrylate, tetrahydrofurfuryl(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritoltetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate,di-(trimethylolpropane tetra(meth)acrylate), propoxylated glyceroltri(meth)acrylate, beta-carboxyethyl (meth)acrylate, bisphenol Aethoxylate di(meth)acrylate, ethoxylated neopentyl glycoldi(meth)acrylate, propoxylated neopentyl glycol di(meth)acrylate,di-(trimethylolpropane tetra(meth)acrylate) or combination thereof.Preferred olefinic monomers include trimethylolpropanetri(meth)acrylate, bisphenol A ethoxylate di(meth)acrylate, propoxylatedglycerol tri(meth)acrylate, trimethylolpropane ethoxylatetri(meth)acrylate, di-(trimethylolpropane tetra(meth)acrylate), orcombinations thereof. The olefinic monomer may contain a (C₁-C₁₅)alcohol radical such as hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl,1-hydroxypropyl, 2-hydroxypropyl, 3-hydroxypropyl, 1-hydroxybutyl,4-hydroxybutyl, 1-hydroxypentyl, 5-hydroxypentyl, 1-hydroxyhexyl,6-hydroxyhexyl, 1,6-dihydroxyhexyl, 1,4-dihydroxybutyl, and the like.

Exemplary allyl ether monomers contain one or more allyl ether groupswhich typically are bonded to a core structural group which can be basedon a wide variety of polyhydric alcohols. Non-limiting examples ofpolyhydric alcohols include neopentyl glycol, trimethylolpropane,ethylene glycol, propylene glycol, butylene glycol, diethylene glycol,trimethylene glycol, triethylene glycol, trimethylolethane,pentaerythritol, dipentaerythritol, di-trimethylolpropane, glycerol,propoxylated glycerol, diglycerol, 1,4-butanediol, 1,6-hexanediol,1,4-cyclohexanedimethanol, and any of the other polyols mentioned abovein connection with the (meth)acrylate esters. Other exemplary allylether monomers include hydroxyethyl allyl ether, hydroxypropyl allylether, trimethylolpropane monoallyl ether, trimethylolpropane diallylether, trimethylolethane monoallyl ether, trimethylolethane diallylether, glycerol monoallyl ether, glycerol diallyl ether, pentaerythritolmonoallyl ether, pentaerythritol diallyl ether, pentaerythritol triallylether, 1,2,6-hexanetriol monoallyl ether, 1,2,6-hexanetriol diallylether, and the like. Preferred allyl ethers include poly propoxylatedand ethoxylated forms of allyl ethers.

Exemplary vinyl ether monomers contain one or more vinyl ether groupsand include 4-hydroxybutyl vinyl ether, 1,4-cyclohexanedimethanolmonovinyl ether, 1,4-cyclohexanedimethanol divinyl ether, ethyleneglycol monovinyl ether, ethylene glycol divinyl ether, diethylene glycolmonovinyl ether, diethylene glycol divinyl ether, triethylene glycoldivinyl ether, and the like. Preferred vinyl ether monomers includepropoxylated or ethoxylated forms of vinyl ether monomers.

The olefinic compounds are curable by radiation, e.g., visible light,ultra violet light, electron beam, and the like. An initiator system isnot required for electron beam curing but for other radiation sourcestypically will be chosen based on the particular type of curing energy(e.g., UV, visible light or other energy) and curing mechanism (e.g.,free-radical, cationic or other curing mechanism) employed. Thus, in onepreferred embodiment, the coating system is electron beam curable anddoes not require an initiator. In another preferred embodiment, thecoating system is UV curable and free-radically polymerizable, andincludes a UV photoinitiator system which generates free radicals inresponse to UV light and thereby cures the coating. Exemplaryphotoinitiator's, coinitiator's or synergists are disclosed in U.S.patent application Ser. No. 11/342,412.

The disclosed coating systems or coating compositions preferably containabout 2 to about 50% by weight separate olefinic compounds based on thetotal weight of the non-volatile components in the coating system, morepreferably about 5 to about 40% by weight and most preferably about 10to about 35% by weight.

Other optional components for use in the coating systems herein aredescribed in Koleske et al., Paint and Coatings Industry, April, 2003,pages 12-86. Typical performance enhancing additives that may beemployed include surface active agents, pigments, colorants, dyes,surfactants, dispersants, defoamers, thickeners, heat stabilizers,leveling agents, coalescents, biocides, mildewcides, anti-crateringagents, curing indicators, plasticizers, fillers, sedimentationinhibitors, ultraviolet light absorbers, optical brighteners, and thelike to modify properties.

The first coating composition is preferably applied to the substrate ata dry film weight of between about 6 and 60 gm/m², more preferablybetween about 4 and 45 gm/m², and most preferably between about 3 and 30gm/m². A recommended thickness of the first coating system after it isdried or otherwise hardened is about 2 to about 75 micrometers and morepreferably about 3 to about 30 micrometers, most preferably about 3 toabout 20 micrometers, and optimally about 4 to about 13 micrometers.

Exemplary coating compositions that can be used in the first coatingsystems are listed below. Exemplary coating compositions may alsocontain optional additives (e.g., defoamers, wetting agents, flattingagents, dyes, pigments, etc.) This is not intended to be an exhaustivelist of examples of aqueous based coating compositions. The examplesinclude compositions having the following major ingredients:

-   -   A Latex polymer and aliphatic epoxy resin system;    -   B Latex polymer, aliphatic epoxy resin system, and silicate        salt;    -   C Epoxy-functional latex system;    -   D Epoxy-functional latex system and silicate salt; and    -   E Epoxy-functional latex system, aliphatic epoxy resin, and        silicate salt.

Compositions A2 to C2—The aforementioned exemplary coating compositionsmay further include one or more optional olefinic compounds and aninitiator. Exemplary olefinic compounds include those described above,as well as multi-functional olefinic compounds (e.g., di- and tri- andtetra-functional (meth)acrylates). Preferred such olefinic monomersinclude trimethylolpropane tri-acrylate (TMPTA), di-trimethylolpropanetetra-acrylate (di-TMPTA) (both available from Sartomer), propoxylatedglycerine triacrylate (available from Sartomer as SR 9020 and SR 9021),the methacrylate versions of these, mixtures thereof, and the like.Exemplary initiators include redox, thermal, or radiation activatedinitiators such as photoinitiators, Among photoinitiators suitable foruse in the present invention with resins having (meth)acrylate or allylether functional groups are alpha-cleavage type photoinitiators andhydrogen abstraction type photoinitiators. The photoinitiator mayinclude other agents such as a coinitiator or photoinitiator synergistthat aid the photochemical initiation reaction. Suitable cleavage typephotoinitiators include alpha, alpha-diethoxyacetophenone (DEAP),dimethoxyphenylacetophenone (commercially available under the tradedesignation IRGACURE™ 651 from Ciba Corp., Ardsley, N.Y.),hydroxycyclo-hexylphenylketone (commercially available under the tradedesignation IRGACURE 184 from Ciba Corp.),2-hydroxy-2-methyl-1-phenylpropan-1-one (commercially available underthe trade designation DAROCUR™ 1173 from Ciba Corp.), a 25:75 blend ofbis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphine oxide and2-hydroxy-2-methyl-1-phenylpropan-1-one (commercially available underthe trade designation IRGACURE 1700 from Ciba Corp.), a 50:50 blend of2-hydroxy-2-methyl-1-phenylpropan-1-one and2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO, commerciallyavailable under the trade designation DAROCUR 4265 from Ciba Corp.),phosphine oxide, 2,4,6-trimethyl benzoyl (commercially available underthe trade name IRGACURE 819 and IRGACURE 819DW from Ciba Corp.),2,4,6-trimethylbenzoyl-diphenylphosphine oxide (commercially availableunder the trade designation LUCIRIN from BASF Corp., Mount Olive, N.J.),and a mixture of 70% oligo2-hydroxy-2-methyl-4-(1-methylvinyl)phenylpropan-1-one and 30%2-hydroxy-2-methyl-1-phenylpropan-1-one) (commercially available underthe trade designation KIP 100 from Sartomer, Exton, Pa.). Suitablehydrogen abstraction-type photoinitiators include benzophenone,substituted benzophenones (such as that commercially available under thetrade designation ESCACURE TZT from Fratelli-Lamberti, sold by Sartomer,Exton, Pa.), and other diaryl ketones such as xanthones, thioxanthones,Michler's ketone, benzil, quinones, and substituted derivatives of allof the above. Preferred photoinitiators include DAROCUR 1173, KIP 100,benzophenone, and IRGACURE 184. A particularly preferred initiatormixture is commercially available under the trade designation IRGACURE500 from Ciba Corp., which is a mixture of IRGACURE 184 andbenzophenone, in a 1:1 ratio. This is a good example of a mixture of analpha-cleavage type photoinitiator and a hydrogen abstraction-typephotoinitiator. Other mixtures of photoinitiators may also be used inthe coating compositions of the present invention. Camphorquinone is oneexample of a suitable photoinitiator for curing a coating compositionwith visible light.

The first coating system can be applied as a single coating compositionor as multiple applications of more than one coating compositions. In apreferred embodiment, the composition is provided as a two-partcomposition and the components are either mixed prior to use or appliedaccording to the methods described in International Patent ApplicationSerial No. PCT/US2007/002347. The specific application and order ofapplication of the selected coating compositions can be readilydetermined by a person skilled in the art. Exemplary descriptions ofthese aqueous based coating systems are described below.

An example of a first coating system for preparing a coated articleincludes water, a latex polymer, an aliphatic epoxy resin system,optionally a silicate salt, optional additives (e.g., defoamers, wettingagents, flatting agents, dyes, pigments, etc.), and optionally one ormore olefinic monomers and an initiator. The coated substrate may thenbe coated with a second coating system (e.g., a primer or topcoatcomposition).

Specific application routes for preparing the coated articles include:

-   -   1) Apply a first coating composition and dry to remove at least        a portion of the water, and optionally subject the first coating        system to a UV cure;    -   2) Apply a first coating composition, apply one or more        additional first coating composition(s) or one or more second        coating system(s), and dry to remove at least a portion of the        water, and optionally subject the entire coating system to UV        cure; and    -   3) Apply a first coating composition and dry to remove at least        a portion of the water, apply one or more additional first        coating composition(s) and/or one or more second coating        system(s) and dry to remove at least a portion of the water, and        optionally subject the entire coating system to UV cure.

Accordingly, coated articles can be prepared by applying the firstcoating system as a single coating composition or the first coatingsystem can be applied as multiple compositions. It is also possible toapply multiple layers of the first coating systems. In first coatingsystems using multiple coating compositions or layers of suchcompositions, (i) the applied coating composition(s) can be dried (toremove at least a portion of the water (solvent)) prior to curing and/oraddition of one or more additional coating compositions, or (ii) thecoating composition(s) can be applied prior to drying the previouslyapplied coating composition(s), thus allowing the coating compositionsto mix at an interface.

The disclosed coating composition(s) are preferably applied at about 5to 60% solids by weight based on the total weight of the non-volatilecomponents, more preferably at about 10 to 50% solids, and mostpreferably at about 10 to 40% solids.

If desired, a second coating system (e.g., a topcoat or a primer and atopcoat) may be applied to the first coating system. Preferred secondcoating systems may be formulated using (i) functionalized latexpolymer's such as are described herein and in published U.S. PatentApplication Nos. 2006/0135684 A1, 2006/0135686 A1, which are hereinincorporated by reference; (ii) “multistage” latex polymers; and (iii)functionalized “multistage” latex polymers, such as are described hereinand in published U.S. Patent Application No. 2007/0110981 A1,Functionalized latex polymers, if used, preferably contain one or moreacetoacetyl groups, carboxylic acid groups, amine groups, epoxy groups,hydroxyl groups, and combinations there of.

Primers may include pigments or be applied as a clear coating. In oneembodiment, the primer can be formulated using low cost extenderpigments at a high PVC level (e.g., greater than 45% pigment). This typeof system can have an advantageous overall cost, e.g., when the extenderpigments are lower cost than the binder. In another embodiment, theprimer can be formulated as a clear coating or as a low PVC levelcoating (e.g., a coating preferably having less than about 15% PCV). Ina preferred embodiment, the applied dry or otherwise hardened filmthickness of the primer is about 2 to about 75 micrometers, morepreferably about 3 to about 30 micrometers, most preferably about 3 toabout 20 micrometers, and optimally about 4 to about 13 micrometers.

In one preferred embodiment, the coating composition(s) contain afunctionalized latex polymer that incorporates acetoacetylfunctionality. Acetoacetyl functionality may be incorporated into thepolymer through the use of: acetoacetoxyethyl acrylate,acetoacetoxypropyl methacrylate, allyl acetoacetate, acetoacetoxybutylmethacrylate, 2,3-di(acetoacetoxy)propyl methacrylate,2-(acetoacetoxy)ethyl methacrylate, t-butyl acetoacetate, diketene, andthe like, or combinations thereof. In certain embodiments, theacetoacetyl functional latex polymer is preferably prepared throughchain-growth polymerization, using, for example, 2-(acetoacetoxy)ethylmethacrylate (AAEM). Preferred latex polymers include at least 0.5weight % acetoacetyl functionality based on the total weight of thelatex polymer, more preferably 0.5 to 5 weight % acetoacetylfunctionality based on the total weight of the latex polymer, and mostpreferably about 1 to 4 weight % acetoacetyl functionality based on thetotal weight of the latex polymer. Such functionalized latex polymersare described in U.S. patent application Ser. Nos. 11/300,070 and11/342,412. In general, any polymerizable hydroxy functional or otheractive hydrogen containing monomer can be converted to the correspondingacetoacetyl functional monomer by reaction with diketene or othersuitable acetoacetylating agent (see, e.g., Comparison of Methods forthe Preparation of Acetoacetylated Coating Resins, Witzeman, J. S.; DellNottingham, W.; Del Rector, F. J. Coatings Technology; Vol, 62, 1990,101 (and references contained therein)). In preferred coatingcompositions, the acetoacetyl functional group is incorporated into thepolymer via 2-(acetoacetoxy)ethyl methacrylate, t-butyl acetoacetate,diketene, or combinations thereof.

The functionalized latex polymer can be prepared through chain-growthpolymerization, using one or more olefinic monomers such as aredescribed above for the first coating system.

If desired, the functionalized latex polymer may be a multistage latexpolymer. Exemplary multistage latex polymer compositions contain atleast two polymers of different glass transition temperatures (e.g.,different Tg's) and may be prepared via emulsion polymerization usingmany of the aforementioned monomers. In one preferred embodiment, thelatex will include a first polymer stage (the “soft stage”) having a Tgbetween about −65 and 30° C., more preferably between about −5 and 25°C., and a second polymer stage (the “hard stage”) having a Tg betweenabout 30 and 230° C., more preferably between about 30 and 105° C.Multistage latexes are typically produced by sequential monomer feedingtechniques. For example, a first monomer composition is fed during theearly stages of the polymerization, and then a second different monomercomposition is fed during the later stages of the polymerization. Incertain embodiments, it may be favorable to start the polymerizationwith a high Tg monomer composition and then switch to a low Tg monomercomposition, while in other embodiments, it may be favorable to startthe polymerization with a low Tg monomer composition and then switch toa high Tg monomer composition.

Numerous hard and soft stages may also be utilized. For example, incertain compositions it may be beneficial to polymerize two differentlow Tg soft stage monomer compositions after the hard stage polymer isformed. The first soft stage may be a prepared with a monomercomposition Tg close to room temperature (e.g., 20° C.) and the secondsoft stage may be prepared with monomer composition Tg well below roomtemperature (e.g., less than 5° C.). While not intending to be bound bytheory, it is believed that this second soft stage polymer assists withimproving coalescence of the latex polymer particles.

It may also be advantageous to use a gradient Tg latex polymer, whichwould contain an almost infinite number of Tg stages. For example, onemay start with a high Tg monomer composition and then at a certain pointin the polymerization start to feed the low Tg soft stage monomercomposition into the high Tg hard stage monomer feed. The resultingmultistage latex polymer will have a gradient Tg from high to low. A“power feed” process may be used to prepare such compositions. Agradient Tg polymer may also be used in conjunction with multiplemultistage Tg polymers. As an example, one may prepare a high Tg monomerfeed (F1) and a low Tg monomer feed (F2). One would begin to feed F1into the latex reactor vessel and initiate polymerization. At a certainperiod during the F1 feed, one would then feed F2 into F1 wherein the F2feed rate is faster than the overall feed rate of F1+F2 into the reactorvessel. Consequently, once the F2 feed into F1 is complete, the overallTg of the F1+F2 monomer feed blend will be a lower Tg “soft stage”monomer composition.

Multistage latex polymer compositions preferably include about 5 to 95weight % soft stage polymer morphology on total polymer weight, morepreferably about 50 to 90 weight % soft stage polymer morphology ontotal polymer weight, and most preferably about 60 to 80 weight % softstage polymer morphology on total polymer weight.

Multistage latex polymer compositions preferably include about 5 to 95weight % hard stage polymer morphology on total polymer weight, morepreferably about 10 to 50 weight % hard stage polymer morphology ontotal polymer weight, and most preferably about 20 to 40 weight % hardstage polymer morphology on total polymer weight.

The multistage latex polymer compositions preferably include at leastabout 10 wt. %, more preferably at least about 25 wt. %, and yet morepreferably at least about 35 wt. % multistage latex polymer based on thetotal composition solids. Exemplary topcoat compositions also preferablyinclude less than 100 wt. %, more preferably less than about 85 wt. %,and yet more preferably less than about 80 wt. % multistage latexpolymer, based on the total composition solids.

The multistage latex polymer is preferably prepared through chain-growthpolymerization, using one or more ethylenically unsaturated monomers asmentioned above. The ratios of the monomers may be adjusted to providethe desired level of “hard” or “soft” segments. In general, the Foxequation may be employed to calculate the theoretical Tg of the monomercomposition being fed. For example, a soft segment may be introduced byproviding a monomer composition containing 5 to 65 parts butyl acrylate,20 to 90 parts butyl methacrylate, 0 to 55 parts methyl methacrylate, 0to 5 parts (meth)acrylic acid and 0 to 20 parts AAEM. In contrast, ahard segment may be introduced by providing a monomer compositioncontaining 0 to 20 parts butyl acrylate, 0 to 40 parts butylmethacrylate, 45 to 95 parts methyl methacrylate, 0 to 5 parts(meth)acrylic acid and 0 to 20 parts AAEM. The aforementionedcompositions are illustrative of this concept and other compositions canbe used in the practice of this invention. A preferred embodiment wouldcontain at least 15 weight % butyl methacrylate based upon total latexpolymer solids.

The functionalized multistage latex polymer preferably incorporatesacetoacetyl functionality, which may be incorporated into the multistagepolymer as described above.

The functionalized latex polymers described above (whether single stageor multistage) may be stabilized by one or more nonionic or anionicemulsifiers (e.g., surfactants), used either alone or together as wasdescribed above.

The multistage latex polymer may also be prepared with a high Tgalkali-soluble polymer hard stage. Alkali-soluble polymer's may beprepared by making a polymer with acrylic or methacrylic acid or otherpolymerizable acid monomer (usually greater than 10%) and solubilizingthe polymer by addition of ammonia or other base. Examples ofalkali-soluble support polymers are JONCRYL 675 and JONCRYL 678. A lowTg soft stage monomer composition could then be polymerized in thepresence of the hard stage alkali-soluble polymer to prepare amultistage latex polymer. A water-soluble free radical initiator istypically used in the chain growth polymerization of the functionalizedlatex polymer.

First and second coating compositions may also contain an optionalcoalescent and many coalescents are known in the art. The optionalcoalescent is preferably a low VOC coalescent such as is described inU.S. Pat. No. 6,762,230. The coating compositions preferably include alow VOC coalescent in an amount of at least about 0.5 weight %, morepreferably at least about 0.75 weight %, and yet more preferably atleast about 1.0 weight % based upon total compositional solids. Thecoating compositions also preferably include a low VOC coalescent in anamount of less than about 20 weight %, more preferably less than about17 weight %, and yet more preferably less than about 15 weight %, basedupon total compositional solids.

For some applications, a coating that is opaque, colored, pigmented orhas other visual characteristics is desired. Agents to provide suchproperties can also be included in the coating compositions, Pigmentsfor use with the disclosed coating compositions are known in the art.Exemplary pigments include titanium dioxide white, carbon black,lampblack, black iron oxide, red iron oxide, yellow iron oxide, browniron oxide (a blend of red and yellow oxide with black), phthalocyaninegreen, phthalocyanine blue, organic reds (such as naphthol red,quinacridone red and toulidine red), quinacridone magenta, quinacridoneviolet, DNA orange, or organic yellows (such as Hansa yellow). Thecomposition can also include a gloss control additive or an opticalbrightener, such as that commercially available under the tradedesignation UVITEX OB from Ciba-Geigy.

Certain embodiments can include fillers or inert ingredients in thecoating composition. Fillers and inert ingredients include, for example,clay, glass beads, calcium carbonate, talc, silicas, organic fillers,and the like. Fillers extend, lower the cost of, alter the appearanceof, or provide desirable characteristics to the composition before andafter curing. Exemplary fillers are known to those of skill in the artor can be determined using standard methods. Fillers or inertingredients are preferably present in an amount of at least 0.1 weight%, based on the total weight of the coating composition. Fillers orinert ingredients are preferably present in an amount of no greater than40 weight %, based on the total weight of the coating composition.

The disclosed coating systems may also include other ingredients thatmodify properties of the curable coating composition as it is stored,handled, or applied, and at other or subsequent stages. Waxes, flattingagents, mar and abrasion additives, and other similar performanceenhancing additives may be employed as required in amounts effective toupgrade the performance of the cured coating and the coatingcomposition. Desirable performance characteristics of the coatinginclude chemical resistance, abrasion resistance, hardness, gloss,reflectivity, appearance, or combinations of these characteristics, andother similar characteristics.

The coating systems may be applied by any number of applicationtechniques including but not limited to brushing (e.g., using a brushcoater), direct roll coating, reverse roll coating, mist coating, floodcoating, vacuum coating, curtain coating and spraying. The varioustechniques each offer a unique set of advantages and disadvantagesdepending upon the substrate profile, morphology and tolerableapplication efficiencies. Lower viscosities facilitate uniform filmcontrol. The applied film thickness may be controlled, for example, byvarying the application rate.

It is preferred that the coated articles are coated on at least onemajor surface with the epoxy coating system. More preferably, the coatedarticles are coated on a major surface and up to four minor surfacesincluding any edges. Most preferably, the coated articles are coated onall (e.g., both) major surfaces, and up to four minor surfaces includingany edges.

A topcoat or primer and topcoat may be applied directly to the epoxycoating system. The coating systems and coating compositions describedherein may be used in place of or in addition to coatings that the priorart has categorized as “sealers,” “primers” and “topcoats.” However, thesystems and compositions may not fit neatly into any category per se andsuch terms should not be limiting. A preferred thickness for the driedor otherwise hardened topcoat is between about 20 and about 200micrometers, preferably between about 25 and about 120 micrometers, morepreferably between about 30 and about 100 micrometers, and mostpreferably between about 35 and about 75 micrometers.

Wet adhesion testing and “freeze-thaw” cycles have been shown, underlaboratory conditions, to simulate long-term outdoor exposureencountered in northern climates. A Wet Adhesion Test may be carried outas follows to evaluate adhesion of the coating system after a coatedcement fiberboard substrate has been saturated with water. According tothis test procedure, coated substrates (e.g., fiber cement boards) aresoaked in room temperature water for 24 hours. After soaking, the boardsare removed from the water and kept at room temperature for 24 hours. Asix-inch (15.24 cm) length of 3M HD 250 tape is applied to the surfaceof the board with the long axis of the tape in the direction of anyembossing patterns that may be present. The tape is firmly pressed ontothe board ensuring full contact. The tape is then removed by quicklypulling it off at a 90-degree angle to the board. “Wet Adhesion”performance is rated based on the percent of coating removed from thecement board. Performance is further assessed by noting where anyfailure occurs. For example, failure may occur between interfacialcoating layers, between the coating and the surface of the board, orwithin the board itself. Preferred coating systems or coatingcompositions typically have less than 25% coating removal, morepreferably less than 15% coating removal. In addition, the failurepreferably is within the board as indicated by a significant amount offiber from the board adhering to the removed coating.

Preferred coated articles can withstand at least 30 freeze-thaw cycles,when tested according to ASTM D6944-03, Test Method A. As written, thisASTM test method recites a 30-cycle sequence. However, rather thansimply grade a specimen as a “pass” at the end of 30 cycles, the testdesirably is lengthened to include additional cycles. More preferably,the coated articles can withstand at least 75 freeze-thaw cycles, mostpreferably at least 125 freeze-thaw cycles and optimally at least 175freeze-thaw cycles.

The disclosed coating systems or coating compositions preferably haveimproved, viz., lower, volatile organic content (VOC). The coatingsystems or coating compositions desirably have a VOC of less than about5%, based on the total weight of the coating system, preferably a VOC ofless than about 2%, more preferably a VOC of less than about 0.5%.Volatile organic compounds are defined in U.S. Pat. No. 6,048,471(Henry) and in the U.S. Federal Register Jun. 16, 1995, volume 60,number 111.

Preferred compositions of the second coating system include less than 10weight %, more preferably less than 7 weight %, and most preferably lessthan 5 weight % volatile organic compounds (VOC) based upon the totalweight of the composition. In addition, these compositions may alsocontain an optional coalescent, preferably a low VOC coalescent such asis described in U.S. Pat. No. 6,762,230.

Having thus described the preferred embodiments of the presentinvention, those of skill in the art will readily appreciate that theteachings found herein may be applied to yet other embodiments withinthe scope of the claims hereto attached.

The invention will be described by the following non-limiting examples.Unless otherwise indicated, all parts and percentages are by weight.

EXAMPLES Example 1 Runs: 1a and 1b

Run 1a: A reactor was charged with 758 parts of deionized water and 1.6parts Triton X-405. The reaction mixture was heated to 75° C. under anitrogen blanket. During heating, a pre-emulsion was formed containing:246 parts of deionized (DI) water, 31 parts of Triton X-405, 11.2 partsRHODAPON UB, 0.7 parts sodium persulfate, 304 parts of styrene, 130parts of methyl methacrylate, 204 parts of butyl acrylate, and 13 partsof methacrylic acid. Once the reaction mixture reaches 75° C., 1.6 partsof sodium persulfate was added to the reactor and the monomer feedstarted for a 3.5 hour feed rate. The reaction temperature was heldbetween 80° C. to 85° C., during polymerization. Once the pre-emulsionfeed was complete, the container was rinsed with 20 parts of deionizedwater and the reaction was held 30 minutes. A post reaction consistingof 0.7 parts t-butyl hydroperoxide mixed with 20 parts of deionizedwater and 0.5 parts of isoascorbic acid mixed with 20 parts of deionizedwater was then added over 30 minutes. The resulting latex polymer wasthen cooled to below 30° C. and poured into two containers.

Run 1b: To 1000 parts of the latex from Example 1a, 108 parts of HELOXY™48 was added over 5-10 minutes and the mixture held for 1 hour.

Example 2 Runs 2a-2c

Run 2a (Comparative Example): A latex composition was prepared by mixingthe following ingredients: 44 parts water and 56 parts of latex from Run1a.

Run 2b: A two-part “epoxy-amine” composition was prepared by mixing thefollowing ingredients: Part ‘A’ contains 51.6 parts of latex from Run1b; and Part ‘B’ contains 46.6 parts water and 1.8 parts EPIKURE™ 3295amine from Hexion.

Run 2c: A two-part “epoxy-amine” composition was prepared by mixing thefollowing ingredients: Part ‘A’ contains 36.1 parts latex from Run 1b;and Part ‘B’ contains 36.8 parts water, 25.8 parts potassium silicate(KASIL 1); and 1.3 parts EPIKURE 3295 amine from Hexion.

Equal parts by weight of ‘A’ and ‘B’ are mixed and allowed to sit for a10-minute induction period before application to a substrate. Inpreferred embodiments, the coating is then applied to a fiber cementarticle at a theoretical dry film thickness of 0.00127 to 0.001778 cm(0.5 to 0.7 mils) by either a single coating application or by two ormore coating applications, and a portion of the water is removed, eitherby air drying, a heated drying stage or by application to a warmsubstrate (e.g., about 38° C.). The coated substrate may then betopcoated, e.g., using a topcoat as disclosed in U.S. patent applicationSer. No. 11/560,329.

Example 3 Acetoacetyl Functional Latex Polymer

A reactor was charged with 567 parts of deionized water, and 1.5 partsRHODAPON™ UB. The reaction mixture was heated to 75° C. under a nitrogenblanket. During heating, a pre-emulsion was formed containing: 331 partsof deionized water, 56.8 parts of RHODAPON UB, 0.9 parts ammoniumpersulfate, 149 parts of 2-ethyl hexyl acrylate, 732 parts of butylmethacrylate, 28.1 parts of AAEM, and 28.1 parts of methacrylic acid.Once the reaction mixture reaches 75° C., 2.8 parts of ammoniumpersulfate was added to the reactor and the monomer feed started for a 3hour feed rate. The reaction temperature was held between 80° C. to 85°C., during polymerization. Once the pre-emulsion feed was complete, thecontainer was rinsed with 20 parts of deionized water and the reactionwas held 30 minutes. A post reaction consisting of 0.9 parts t-butylhydroperoxide mixed with 20 parts of deionized water and 0.7 parts ofisoascorbic acid mixed with 20 parts of deionized water were added over30 minutes. The resulting latex polymer was then cooled to 40° C. and28% concentrate ammonia was added to adjust the pH to 7.5-8.5 anddeionized water was added to adjust the weight solids to 48%.

Example 4 Multistage Acetoacetyl Functional Latex Polymer

A reactor was charged with 547 parts of deionized water, and 15 partsRHODAPON UB. The reaction mixture was heated to 75° C. under a nitrogenblanket. During heating, pre-emulsion 1 was formed containing: 215 partsof deionized water, 37 parts of RHODAPON UB, 0.6 parts ammoniumpersulfate, 103 parts of 2-ethyl hexyl acrylate, 470 parts of butylmethacrylate, 18 parts of AAEM, and 18 parts of methacrylic acid.Pre-emulsion 2 was formed containing: 116 parts of deionized water, 20parts of RHODAPON UB, 0.3 parts ammonium persulfate, 223 parts ofmethylmethacrylate, 85 parts of butyl methacrylate, 10 parts of AAEM,and 10 parts of methacrylic acid. Once the reaction mixture reaches 75°C., 2, 8 parts of ammonium persulfate was added to the reactor and thepre-emulsion 1 started for a 2 hour feed rate. Once pre-emulsion 1 wasadded, the container was rinsed with 20 parts deionized water andpre-emulsion 2 started for a 1 hour feed rate. The reaction temperaturewas held between 80° C. to 85° C., during polymerization. Once thepre-emulsion 2 feeds was complete, the container was rinsed with 20parts of deionized water and the reaction was held 30 minutes. A postreaction consisting of 0.9 parts t-butyl hydroperoxide mixed with 20parts of deionized water and 0.7 parts of isoascorbic acid mixed with 20parts of deionized water was then added over 30 minutes. The resultinglatex polymer was then cooled to 40° C. and a 28% concentrate ammoniawas added to adjust the pH to 7.5-8.5 and deionized water was added toadjust the weight solids to 48%.

Example 5a-c Paint Compositions

In a mixing vessel equipped with a high-speed mixer and dispersionblade, was added the following ingredients in order (parts by weight):

Ingredient Example 5a Example 5b Example 5c Water 101 101 101 CellosizeQP Thickener 0.8 0.8 0.8 09-L

The above ingredients were mixed for 5 minutes or until homogenous, andthen the following ingredients were added (parts by weight):

Example Ingredient Example 5a Example 5b 5c Dehydran 1620 Defoamer 1.51.5 1.5 Texanol Co-solvent 15 15 15 Disperbyk 190 Dispersant 7 7 7Ammonia 26 BE Neutralizer 1 1 1 Ti Pure R902-28 Pigment 220 220 220 ASP170 Alum. Extender 85 85 85 Silicate

The above ingredients were mixed at high speed for 15 minutes, and thenthe following ingredients were added (parts by weight):

Example Ingredient Example 5a Example 5b 5c Ammonia 26 BE Neutralizer 11 1

To the above was added the following in order (parts by weight):

Example Example Ingredient Example 5a 5b 5c Water 46.6 46.6 6.9 Example2, Run 1 latex 596.2 — — Example 3 latex — 596.2 — Neocryl XK 90 latex —— 636 Water 16.7 16.7 16.7 Byk 024 Defoamer 1 1 1 Acrysol RM- Thickener1.5 1.5 1.5 2020NPR

The above were mixed for 15 minutes using moderate agitation.

Example 6 Tape Adhesion Test Results

A 15.24×21 cm board sample was prepared for testing as outlined inExample 2 and then a second system applied using the followingtechnique.

Preheat board sample to 43° C. (˜110° F.) using a convection oven set at149° C. (300° F.). Apply approximately 5.2 grams of topcoat by spreadingevenly over the surface of the board using either a bristle or foambrush. Immediately after coating the board, place it in the 149° C.(300° F.) oven until the board surface temperature reaches 60° C. (140°F.). Remove sample and allow to cool to room temperature.

Adhesion test procedures: After a board sample has been sealed,top-coated and dried, it can be tested for coating adhesion using 3Mbrand 250 standard tape. The adhesion of a coating system to the surfaceof a board may be tested after the coating system has been applied andcured/dried to the specifications of the coating system. To the surfaceof the board, was applied a 7.62 cm (3 inch) strip of 3M brand #250standard masking tape. The tape was firmly pressed onto to the boardsurface using either a thumb, applying a minimum of 20.67 kPa (5 psi) tothe full length of the tape for 10 seconds. Two minutes was allowed forthe adhesive to equilibrate on the board surface. After equilibrating,the tape was removed rapidly (equal to or less than 1 second) by pullingit up at a 90 degree angle. Failure was reported as a combination ofcoating adhesion failure and also board surface failure.

Comparative Test Results:

TEST 1 TEST 2 TEST 3 TEST 4 First Example 2, Example 2, Example 2,Example 2, Coat Run 2a Run 2a Run 2a Run 2a Second Example 5a Example 5bExample 5c Duration House Coat Paint from Sherwin Williams % 90% 90% 85%85% Adhesion LossInvention Test Results:

TEST 5 TEST 6 TEST 7 TEST 8 First Example 2, Example 2, Example 2,Example 2, Coat Run 2b Run 2b Run 2b Run 2b Second Example 5a Example 5bExample 5c Duration House Coat Paint from Sherwin Williams % <1% <1% <1% 4-8% Adhesion Loss TEST 9 TEST 10 TEST 11 TEST 12 First Example 2,Example 2, Example 2, Example 2, Coat Run 2c Run 2c Run 2c Run 2c SecondExample 5a Example 5b Example 5c Duration House Coat Paint from SherwinWilliams % <1% <1% 2-5% 1-2% Adhesion Loss

Example 7 Oxirane Functional Latex

A two-piece three necked flask equipped with a stirrer, condenser,thermocouple, and nitrogen inlet was charged with 720 grams of deionizedwater and 1.25 grams of Triton X-405 (Rohm & Haas). The material wasstirred and heated to 80 to 90° C. A monomer mix was prepared separatelyin a 2-liter beaker with agitation. The beaker is charged with 291 gramsof water, 23.8 grams of Triton X-405, 592 grams of styrene, 202 grams ofbutyl acrylate, 16.7 grams of methacrylic acid, and 65.8 grams ofglycidyl methacrylate while mixing to form a pre-emulsion. 2.0 grams ofsodium persulfate was dissolved into the emulsion. At 80-90° C. 2.0grams of sodium persulfate dissolved in 20 grams of deionized water wascharged to the reactor. The monomer emulsion was then fed to the reactorover 3½ hours at 80-90° C. The emulsion was rinsed with 20 grams ofdeionized water. Then the reaction was held for 30 minutes. Tert-butylhydroperoxide, 1.0 gram, was added, followed by a solution of 07 gramsof erythorbic acid and 20 grams of water. After 20-30 minutes, thereaction was cooled and reduced with 20 grams of water. The solids wereadjusted to about 45% by weight. The MFFT of the latex was greater than60° C.

Example 8a-c Coalescing Ability of Aliphatic Epoxy Resin

8a. To 100 grams of the latex formed in Example 7 were added 7.9 gramsof Heloxy 68 and the solids adjusted to 45%.

8b. To 100 grams of the latex formed in Example 7 were added 11.3 gramsof Heloxy 68 and the solids adjusted to 45%.

8c. To 100 grams of the latex formed in Example 7 were added 15 grams ofHeloxy 68 and the solids adjusted to 45%.

Example 7 Example 8a Example 8b Example 8c MFFT >60° C. 21° C. 11° C.<5° C.The aliphatic epoxy resin acts as a coalescent, lowering MFFT andallowing lower VOC formulations to be prepared.

Example 9 Oxirane Functional Latex

A two-piece three necked flask equipped with a stirrer, condenser,thermocouple, and nitrogen inlet was charged with 720 grams of deionizedwater and 1.25 grams of Triton X-405 (Rohm & Haas) The material wasstirred and heated to 80 to 90° C. A monomer mix was prepared separatelyin a 2 liter beaker with agitation. The beaker was charged with 291grams of water, 23.8 grams of Triton X-405, 458 grams of styrene, 336grams of butyl acrylate, and 16.7 grams of methacrylic acid, and 65.8grams of glycidyl methacrylate while mixing to form a preemulsion. 2.0grams of sodium persulfate was dissolved into the emulsion. At 80-90° C.2.0 grams of sodium persulfate dissolved in 20 grams of deionized waterwas charged to the reactor. The monomer emulsion was then fed to thereactor over 3½ hours at 80-90° C. The emulsion was rinsed with 20 gramsof deionized water. The reaction was held for 30 minutes. Tert-butylhydroperoxide, 1.0 gram, was added, followed by a solution of 0.7 gramsof erythorbic acid and 20 grams of water. After 20-30 minutes, thereaction was cooled and reduced with 20 grams of water. The solids wereadjusted to about 45% by weight.

Example 10a-c Pigmented Coating Compositions

A pigment grind paste was made as follows:

Wt. Raw Material Supplier Location % Add the following to a mixturecontainer, apply high shear agitation for 5 minutes: DI Water NA 29.8Attagel 50 Engelhard Iselin, NJ 08830 1.5 After 5 minutes, add thefollowing in order under high agitation: Tamol 731-1 25% Rohm & HaasPhiladelphia, PA 19106-2399 1.5 Tamol 850 Rohm & Haas Philadelphia, PA19106-2399 3.0 Byk 035 Byk (Altana) Wesel Germany 46462 0.9 TitaniumDioxide DuPont Wilmington, DE 42.8 Red Iron Oxide Elementis East St.Louis, IL 62204 3.7 Yellow Iron Elementis East St. Louis, IL 62204 14.0Oxide Carbon Black Elementis East St. Louis, IL 62204 2.8

Example 10a Pigmented Epoxy Modified Coating

Raw Material Supplier Location Wt. % The following were added in orderunder moderate mixing: Example 9 23.3 Paraplex WP-1 Rohm & HaasPhiladelphia, PA 3.7 19106-2399 Mix for 30 minutes, then add thefollowing in order: Grind Paste (From 9.2 Example 11) Epicure 3295Hexion Houston, TX 77082 0.25 DI Water NA 32.9 DI Water (Reduction) NA16.5 Kasil 1 PQ Corporation Valley Forge, PA 14.0 19482-8040

Example 10b Pigmented Epoxy Modified Coating

Wt. Raw Material Supplier Location % The following were added in orderunder moderate mixing: Example 9 22.0 Heloxy 48 3.5 Mix for 30 minutes,and then add the following in order: Grind Paste (From Above) 8.7 DIWater NA 51.3 Kasil 1 PQ Corporation Valley Forge, PA 19482-8040 13.2EPIKURE 3295 Hexion Houston, TX 77082 1.3

Example 10c Pigmented Epoxy Modified Coating

Raw Material Supplier Location Wt. % The following were added in orderunder moderate mixing: Example 9 21.9 Heloxy 68 Hexion Houston, TX 770823.5 Mix for 30 minutes, and then add the following in order: Grind Paste(From Above) 8.7 DI Water NA 51.4 Kasil 1 PQ Corporation Valley Forge,PA 13.2 19482-8040 EPIKURE 3295 Hexion Houston, TX 77082 1.3

The epoxy modified coatings should also provide an improved freeze-thawsystem for fiber cement

Example 11 Tape Adhesion test Results

A 15.24×21 cm board sample was prepared for testing as outlined inExample 2 using the coating prepared in Example 10 and then a secondcoating system applied using the following technique.

Preheat board sample to about 43° C. (˜110° F.) using a convection ovenset at 149° C. (300° F.). Apply approximately 5.2 grams of topcoat byspreading evenly over the surface of the board using either a bristle orfoam brush. Immediately after coating the board, place it in the 149° C.(300° F.) oven until the board surface temperature reaches 60° C. (140°F.). Remove sample and allow the board sample to cool to roomtemperature. The second coating system applied was prepared as describedin Rohm & Haas Formulation W-264-8.

Adhesion Test Procedures:

After a board sample has been sealed, top-coated and dried, it wastested for coating adhesion using 3M brand 250 standard tape after theboard was submerged in room temperature water overnight. To the surfaceof the board, a strip of 3M brand #250 standard masking tape, at least7.62 cm (3 inch) in length, was applied. The tape was firmly pressed tothe board surface applying a minimum of 20.67 kPa (5 psi) (with a thumbor forefinger) to the full length of the tape for 10 seconds. Twominutes were allowed for the adhesive to equilibrate on the boardsurface. After equilibrating, the tape was removed rapidly (equal to orless than 1 second) by pulling it up at a 90 degree angle. Failure wasreported as a combination of coating adhesion failure or board surfacefailure.

TEST 11A TEST 11B TEST 11C First Coat Example 10a Example 10b Example10c % Adhesion Loss <5% 5-10% <5%

The epoxy modified coatings should also provide an improved freeze-thawsystem for fiber cement.

It is also noted that the compositions of the invention can be used withother coating compositions such as, those disclosed in U.S. PatentApplication Nos. 60/764,044, 60/764,131, 60/764,242, and 60/773,482,60/764,103, 60/802,185 and 60/802,186.

All patents, patent applications and literature cited in thespecification are hereby incorporated by reference in their entirety. Inthe case of any inconsistencies, the present disclosure, including anydefinitions therein will prevail. The invention has been described withreference to various specific and preferred embodiments and techniques.However, it should be understood that many variations and modificationsmay be made while remaining within the invention.

What is claimed is:
 1. An aqueous coating system comprising: one or moremultistage latex polymers containing between 50 and 90 wt. % hardsegments having a Tg between 30 and 130° C. and between 10 and 50 wt. %soft segments having a Tg between 0 and 25° C.; an aliphatic epoxy resinsystem having an oxirane functional component that is distinct from theone or more multistage latex polymers, wherein the oxirane functionalcomponent in the aliphatic epoxy resin system has an epoxy equivalentweight less than 1000; and wherein the aqueous coating system includesone or more coating compositions that may be applied in one or morelayers and contains about 2-50 wt. % aliphatic epoxy resin based ontotal solids, and the aqueous coating system when dried isblock-resistant.
 2. The aqueous coating system of claim 1, wherein thethe one or more multistage latex polymers comprise one or more epoxyfunctional groups.
 3. The aqueous coating system of claim 2, wherein atleast one of the latex polymers is made from glycidyl methacrylate,glycidyl acrylate, 4-hydroxybutyl acrylate glycidylether, andcombinations thereof.
 4. The aqueous coating system of claim 1, whereinthe minimum film forming temperature of a blend of the one or moremultistage latex polymers with the oxirane functional component of thealiphatic epoxy resin system is less than about 20° C.
 5. The aqueouscoating system of claim 1, wherein the the one or more multistage latexpolymers comprise acetoacetoxy-functionality.
 6. The aqueous coatingsystem of claim 1, wherein the one or more multistage latex polymerscomprise one or more amine groups.
 7. The aqueous coating system ofclaim 1, wherein the aqueous coating system further comprises about 2 to50 wt. % of a silicate salt; wherein the silicate salt is potassiumsilicate, ammonium silicate, sodium silicate, lithium silicate, ormixtures thereof.
 8. The aqueous coating system of claim 1, wherein theoxirane functional component is the reaction product of an oxiraneprecursor molecule with an alcohol containing material or a carboxylicacid containing material.
 9. The aqueous coating system of claim 8,wherein the oxirane functional component is the reaction product of anoxirane precursor molecule with an alcohol containing material, and atleast a portion of the alcohol containing material is ethylene glycol,propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol,2-methyl-1,3-propanediol, neopentyl glycol, 2,2-butylethyl propanediol,hexanediol, diethylene glycol, dipropylene glycol, polyethylene glycols,polypropylene glycols, cyclohexane dimethylol,2,2,3-trimethylpentanediol, trimethylol propane, ethoxylated trimethylolpropane, propoxylated trimethylol propane, glycerine, propoxylatedglycerine, pentaerythritol, ethoxylated pentaerythritol, propoxylatedpentaerythritol, dipentaerythritol, tripentaerythritol, ethoxylated andpropoxylated dipentaerythritol, ethoxylated and propoxylatedtri-pentaerythritol, ditrimethylolpropane, hydroxypivalylhydroxypivalate, hydrogenated bisphenol A, ethoxylated and propoxylatedhydrogenated bisphenol A, isosorbide, or mixtures thereof.
 10. Theaqueous coating system of claim 8, wherein the oxirane functionalcomponent is the reaction product of an oxirane precursor molecule witha carboxylic acid containing material, and at least a portion of thecarboxylic acid containing material is malonic acid, succinic acid,glutaric acid, sebacic acid, fumaric acid, adipic acid, pimelic acid,hexahydrophthalic acid, 1,3- and 1,4 cyclohexanedicarboxylic acid,orthophthalic acid, isophthalic acid, maleic acid, chlorendic acid,glycolic acid, citric acid, trimellitic acid, lactic acid, caprolactone,or mixtures thereof.
 11. The aqueous coating system of claim 8, whereinthe oxirane functional component has an epoxy equivalent weight of about90 to
 350. 12. A coated article comprising a substrate, at least aportion of which is coated with one or more layers of the aqueouscoating system of claim 1, and one or more layers of a second coatingsystem comprising a latex polymer.
 13. A coated article comprising asubstrate, at least a portion of which is coated with one or more layersof the aqueous coating system of claim 1, and one or more layers of asecond coating system comprising a functionalized latex polymer, amultistage latex polymer, or a functionalized, multistage latex polymer.14. The aqueous coating system of claim 1, wherein the aqueous coatingsystem further comprises one or more olefinic compounds and is radiationcurable.
 15. A coated article comprising a substrate, at least a portionof which is coated with one or more layers of the aqueous coating systemof claim 1, and one or more layers of a second coating system comprising(i) a latex containing primer, (ii) a latex containing topcoat, or (iii)both (i) and (ii).
 16. The coated article of claim 15, wherein thesecond coating system comprises a functionalized latex polymer, amultistage latex polymer or a functionalized, multistage latex polymer.17. The coated article of claim 16, wherein the second coating systemcomprises (i) an acetoacetoxy-functional latex containing primer, or(ii) an acetoacetoxy-functional latex containing topcoat, or (iii) both(i) and (ii).
 18. The aqueous coating system of claim 1 wherein themultistage latex polymer has a hard segment having a Tg between 30 and70° C.
 19. The aqueous coating system of claim 1, wherein the aqueouscoating system contains about 20-80 wt. % latex polymer based on totalsolids.
 20. The aqueous coating system of claim 1, wherein the aqueouscoating system contains about 2-15 wt. % amine crosslinker based ontotal solids with a reactive hydrogen equivalent weight between 20 and500.
 21. The aqueous coating system of claim 1, further comprising oneor more pigments.
 22. The aqueous coating system of claim 1, wherein thealiphatic epoxy resin system acts as a coalescent.
 23. The aqueouscoating system of claim 22, wherein the minimum film forming temperatureof the aqueous coating system is less than about 20° C.
 24. The aqueouscoating system of claim 1, wherein the aliphatic epoxy resin systemlowers the minimum film forming temperature of the aqueous coatingsystem.
 25. The aqueous coating system of claim 24, wherein the minimumfilm forming temperature of the aqueous coating system is less thanabout 30° C.
 26. A coated article comprising a substrate, at least aportion of which is coated with one or more layers of the aqueouscoating system of claim
 1. 27. The coated article according to claim 26,wherein the substrate is cement fiberboard.